using System;
using System.Collections.Generic;

namespace JetBrains.Annotations
{
	/// <summary>
	/// Indicates that marked method builds string by format pattern and (optional) arguments. 
	/// Parameter, which contains format string, should be given in constructor.
	/// The format string should be in <see cref="string.Format(IFormatProvider,string,object[])"/> -like form
	/// </summary>
	[AttributeUsage(AttributeTargets.Constructor | AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
	internal sealed class StringFormatMethodAttribute : Attribute
	{
		private readonly string _formatParameterName;

		/// <summary>
		/// Initializes new instance of StringFormatMethodAttribute
		/// </summary>
		/// <param name="formatParameterName">Specifies which parameter of an annotated method should be treated as format-string</param>
		public StringFormatMethodAttribute(string formatParameterName)
		{
			_formatParameterName = formatParameterName;
		}

		/// <summary>
		/// Gets format parameter name
		/// </summary>
		public string FormatParameterName
		{
			get { return _formatParameterName; }
		}
	}

	/// <summary>
	/// Indicates that the function argument should be string literal and match one  of the parameters of the caller function.
	/// For example, <see cref="ArgumentNullException"/> has such parameter.
	/// </summary>
	[AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false, Inherited = true)]
	internal sealed class InvokerParameterNameAttribute : Attribute
	{
	}

	/// <summary>
	/// Indicates that the marked method is assertion method, i.e. it halts control flow if one of the conditions is satisfied. 
	/// To set the condition, mark one of the parameters with <see cref="AssertionConditionAttribute"/> attribute
	/// </summary>
	/// <seealso cref="AssertionConditionAttribute"/>
	[AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
	internal sealed class AssertionMethodAttribute : Attribute
	{
	}

	/// <summary>
	/// Indicates the condition parameter of the assertion method. 
	/// The method itself should be marked by <see cref="AssertionMethodAttribute"/> attribute.
	/// The mandatory argument of the attribute is the assertion type.
	/// </summary>
	/// <seealso cref="AssertionConditionType"/>
	[AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false, Inherited = true)]
	internal sealed class AssertionConditionAttribute : Attribute
	{
		private readonly AssertionConditionType _conditionType;

		/// <summary>
		/// Initializes new instance of AssertionConditionAttribute
		/// </summary>
		/// <param name="conditionType">Specifies condition type</param>
		public AssertionConditionAttribute(AssertionConditionType conditionType)
		{
			_conditionType = conditionType;
		}

		/// <summary>
		/// Gets condition type
		/// </summary>
		public AssertionConditionType ConditionType
		{
			get { return _conditionType; }
		}
	}

	/// <summary>
	/// Specifies assertion type. If the assertion method argument satisifes the condition, then the execution continues. 
	/// Otherwise, execution is assumed to be halted
	/// </summary>
	internal enum AssertionConditionType
	{
		/// <summary>
		/// Indicates that the marked parameter should be evaluated to true
		/// </summary>
		IS_TRUE = 0,

		/// <summary>
		/// Indicates that the marked parameter should be evaluated to false
		/// </summary>
		IS_FALSE = 1,

		/// <summary>
		/// Indicates that the marked parameter should be evaluated to null value
		/// </summary>
		IS_NULL = 2,

		/// <summary>
		/// Indicates that the marked parameter should be evaluated to not null value
		/// </summary>
		IS_NOT_NULL = 3,
	}

	/// <summary>
	/// Indicates that the marked method unconditionally terminates control flow execution.
	/// For example, it could unconditionally throw exception
	/// </summary>
	[AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
	internal sealed class TerminatesProgramAttribute : Attribute
	{
	}

	/// <summary>
	/// Indicates that the value of marked element could be <c>null</c> sometimes, so the check for <c>null</c> is necessary before its usage
	/// </summary>
	[AttributeUsage(AttributeTargets.Method | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.Delegate | AttributeTargets.Field, AllowMultiple = false, Inherited = true)]
	internal sealed class CanBeNullAttribute : Attribute
	{
	}

	/// <summary>
	/// Indicates that the value of marked element could never be <c>null</c>
	/// </summary>
	[AttributeUsage(AttributeTargets.Method | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.Delegate | AttributeTargets.Field, AllowMultiple = false, Inherited = true)]
	internal sealed class NotNullAttribute : Attribute
	{
	}

	/// <summary>
	/// Indicates that the value of marked type (or its derivatives) cannot be compared using '==' or '!=' operators.
	/// There is only exception to compare with <c>null</c>, it is permitted
	/// </summary>
	[AttributeUsage(AttributeTargets.Interface | AttributeTargets.Class | AttributeTargets.Struct, AllowMultiple = false, Inherited = true)]
	internal sealed class CannotApplyEqualityOperatorAttribute : Attribute
	{
	}

	/// <summary>
	/// When applied to target attribute, specifies a requirement for any type which is marked with 
	/// target attribute to implement or inherit specific type or types
	/// </summary>
	/// <example>
	/// <code>
	/// [BaseTypeRequired(typeof(IComponent)] // Specify requirement
	/// public class ComponentAttribute : Attribute 
	/// {}
	/// 
	/// [Component] // ComponentAttribute requires implementing IComponent interface
	/// public class MyComponent : IComponent
	/// {}
	/// </code>
	/// </example>
	[AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = true)]
	[BaseTypeRequired(typeof(Attribute))]
	internal sealed class BaseTypeRequiredAttribute : Attribute
	{
		private readonly Type[] _baseTypes;

		/// <summary>
		/// Initializes new instance of BaseTypeRequiredAttribute
		/// </summary>
		/// <param name="baseType">Specifies which types are required</param>
		public BaseTypeRequiredAttribute(Type baseType)
			: this(new Type[] { baseType })
		{
		}

		/// <summary>
		/// Initializes new instance of BaseTypeRequiredAttribute
		/// </summary>
		/// <param name="baseTypes">Specifies which types are required</param>
		public BaseTypeRequiredAttribute(params Type[] baseTypes)
		{
			_baseTypes = baseTypes;
		}

		/// <summary>
		/// Gets enumerations of specified base types
		/// </summary>
		public IEnumerable<Type> BaseTypes
		{
			get { return _baseTypes; }
		}
	}

	/// <summary>
	/// Indicates that the marked symbol is used implicitly (e.g. via reflection, in external library),
	/// so this symbol will not be marked as unused (as well as by other usage inspections)
	/// </summary>
	[AttributeUsage(AttributeTargets.All, AllowMultiple = false, Inherited = false)]
	internal class UsedImplicitlyAttribute : Attribute
	{
		readonly ImplicitUseFlags _flags;
		/// <summary>
		/// Gets value indicating what is meant to be used
		/// </summary>
		[UsedImplicitly]
		public ImplicitUseFlags Flags
		{
			get { return _flags; }
		}

		/// <summary>
		/// Initializes new instance of UsedImplicitlyAttribute
		/// </summary>
		public UsedImplicitlyAttribute()
			: this(ImplicitUseFlags.Default)
		{
		}

		/// <summary>
		/// Initializes new instance of UsedImplicitlyAttribute with specified flags
		/// </summary>
		/// <param name="flags">Value of type <see cref="ImplicitUseFlags"/> indicating usage kind</param>
		public UsedImplicitlyAttribute(ImplicitUseFlags flags)
		{
			_flags = flags;
		}
	}

	/// <summary>
	/// Should be used on attributes and causes ReSharper to not mark symbols marked with such attributes as unused (as well as by other usage inspections)
	/// </summary>
	[AttributeUsage(AttributeTargets.Class, AllowMultiple = false, Inherited = true)]
	internal class MeansImplicitUseAttribute : Attribute
	{
		readonly ImplicitUseFlags _flags;
		/// <summary>
		/// Gets value indicating what is meant to be used
		/// </summary>
		[UsedImplicitly]
		public ImplicitUseFlags Flags
		{
			get { return _flags; }
		}

		/// <summary>
		/// Initializes new instance of MeansImplicitUseAttribute
		/// </summary>
		[UsedImplicitly]
		public MeansImplicitUseAttribute()
			: this(ImplicitUseFlags.Default)
		{
		}

		/// <summary>
		/// Initializes new instance of MeansImplicitUseAttribute with specified flags
		/// </summary>
		/// <param name="flags">Value of type <see cref="ImplicitUseFlags"/> indicating usage kind</param>
		[UsedImplicitly]
		public MeansImplicitUseAttribute(ImplicitUseFlags flags)
		{
			_flags = flags;
		}
	}

	/// <summary>
	/// Specify what is considered used implicitly when marked with <see cref="MeansImplicitUseAttribute"/> or <see cref="UsedImplicitlyAttribute"/>
	/// </summary>
	[Flags]
	internal enum ImplicitUseFlags
	{
		/// <summary>
		/// Only entity marked with attribute considered used
		/// </summary>
		Default = 0,

		/// <summary>
		/// Entity marked with attribute and all its members considered used
		/// </summary>
		IncludeMembers = 1
	}
}